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[Familial glomerulonephritis and hereditary deficiency of C2]
Insights
Hereditary C2 complement deficiency is linked to glomerulonephritis, particularly in individuals with homozygous or heterozygous deficiency. This genetic condition increases susceptibility to immune-complex diseases like kidney inflammation.
Area of Science:
- Immunogenetics
- Nephrology
- Complement System Biology
Background:
- Hereditary complement deficiencies can predispose individuals to autoimmune and immune-complex diseases.
- Complement component 2 (C2) deficiency is a known genetic disorder affecting the classical complement pathway.
Observation:
- A family study identified an association between hereditary C2 deficiency and glomerulonephritis in 4 out of 8 children.
- Homozygous C2 deficiency resulted in significantly decreased hemolytic complement (CH50) levels, while heterozygous deficiency showed a slight decrease.
- Normal levels of other complement components (C1q, C4, C3, C5, C1s INA) were observed, with C2 present at intermediate or null rates.
Findings:
- Hemolytic complement (CH50) levels could be restored by adding purified human C2, confirming the deficiency's impact.
- The C2 deficiency genes were linked to specific HLA haplotypes (A10 B18 and A29 B18), though HLA-D alleles differed between parents.
- C2 deficiency was associated with an increased susceptibility to immune-complex diseases, notably glomerulonephritis.
Implications:
- Hereditary C2 deficiency is a significant risk factor for developing glomerulonephritis.
- Understanding the genetic basis of complement deficiencies is crucial for diagnosing and managing immune-complex kidney diseases.
- This research highlights the critical role of the complement system, specifically C2, in immune homeostasis and preventing renal pathology.
Abstract:
The association between glomerulonephritis and hereditary C2 complement deficiency has been found in 4 out of 8 children of a family. The hemolytic complement (CH50) was much decreased in homozygot subjects and slightly decreased in heterozygot. C1q, C4, C3, C5, C1s INA were normal, the C2 was found at an intermediate or null rate; CH50 could be reconstitued by purified human C2. The C2 deficiency genes were associated with HLA A10 B18 (father) and HLA A29 B18 (mother) haplotypes but HLA D allels were different on the 2 haplotypes. The C2 deficiency appears to lead to an increased susceptibility to immune-complexe diseases, specially to glomerulonephritis.